Re: [LEAPSECS] Things to do at about 2005-12-31 23:59:60Z

From: Neal McBurnett <>
Date: Sat, 31 Dec 2005 00:35:02 -0700

On Mon, Dec 19, 2005 at 11:31:22PM +0000, Markus Kuhn wrote:
> I suspect, the basic exercise will be running a little test routines on
> various NTP-synchronized hosts, that log the progression of
> clock_gettime(), gettimeofday(), etc. against whatever hardware counter
> register is available, just to see what actually happens these days at
> the API during a leap second with the very latest kernel versions.

Anyone have software to watch this stuff which they want to share?

> What could show interesting effects during a leap second?
> Of all the normal personal-computer applications, I suspect by far the
> most clock sensitive ones may be streaming audio and video applications
> such as
> - Mediaplayer
> - Realplayer
> - Quicktime
> - Software DVD decoders
> - VoIP (Skype, etc.)

I would think MIDI sequencers or other SMPTE-aware applications would
be worth adding to the mix.

> followed by some types of networked computer games. It is very unlikely
> that any standard computer application will actually display 23:59:60,
> because the POSIX API has no way of communicating such a time stamp,
> which can only be obtained using special leap-second aware system calls
> such as adjtimex().

Hmmm - surely someone has a leap-second-enabled clock for Linux, BSD
or other operating systems. Any pointers out there?

> There are of course countless GPS, GLONASS, DCF77, WWVB, etc. receivers
> to be watched, as well as applications that depend on them.

Yes - I wonder if we'll notice any NTP stratum 1 clocks out there with
broken clock interface drivers?

Anyone know if any GPS units (like the GPSmap 60) display second "60"
properly in their time display? Hard to decide what to be watching
during that crucial second....

> If you have a counter connected to the power grid, at least in most of
> Europe (i.e., the UCTE 50 Hz network), you should see that -- thanks to
> the leap second -- the frequency will during the following day be set
> slightly lower, to ensure that European electricity consumers pay back
> the free 50 cycles they got during the leap second. (But it may take a
> few days of averaging until this long-term phase shift by 50 cycles
> actually becomes clearly visible in the general phase/frequency noise of
> the power grid.)

What is the story in the US these days?

> Owners of long-wave radios for the 40-70 kHz range with BFO, as well
> as owners of shortwave radios, can listen to the additional leap second
> pulse being transmitted by the relevant time and frequency stations, as
> well as the DUT1 change immediately afterwards.
> How about calling various speaking clocks all over the world and measure
> how long it takes until they notice the leap second.
> Will the BBC broadcast seven beeps at the end of this year, instead of six?
> What about Big Ben?
> What else could (or should) react to a leap second?

I heard today from Tom O'Brian, Chief of the NIST Time and Frequency
Division here in Boulder Colorado that the clocks on the walls all
over NIST in Boulder are incapable of showing the "60". There is a
device in one of their labs (I didn't ask exactly what) that will show
it and they'll make a videotape of it. I suggested a webcam for the
next time around and he said they'd look in to that.

In an interview for the KCNC (Denver Channel 4) TV audience he
suggested watching their leap-second-enabled java applet at

> It might be fun to compile a comprehensive documentary here on how the
> leap second is implemented in practice today ...

Take notes and post your reports, folks!


Neal McBurnett
Signed and/or sealed mail encouraged. GPG/PGP Keyid: 2C9EBA60

> Markus
> --
> Markus Kuhn, Computer Laboratory, University of Cambridge
> || CB3 0FD, Great Britain
Received on Fri Dec 30 2005 - 23:36:25 PST

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